a b s t r a c t
In the present study, laboratory scale biogas production from rice husks (RH) generated from different
rice mills was investigated using cow rumen fluid as a source of inoculum. The effects of various parameters
such as water dilution, initial pH, heavy metals and nitrogen sources on digester performance
were evaluated. Feedstock to water dilution ratio of 1:6 w/v and initial pH 7 gave the maximum biogas
yield of 382 and 357 mL/day, respectively. Addition of heavy metals (Ni2þ, Zn2þ, and Cu2þ) enhanced
digester performance with Ni2þ (100 ppm) giving the best biogas yield. The maximum values of biogas
production rate were 30 and 69 mL/day for the control and poultry droppings, respectively, after two
days while urea gave 8 mL/day on day four. The use of poultry droppings (PD) as nitrogen supplements
encouraged biogas generation. Therefore, rice husks offer an alternative source of energy to agricultural
farmers.